The proposed research will use biomagnetic susceptometry - a method first conceived and subsequently developed in our laboratories - for the clinical investigation of human iron metabolism. Direct, non-invasive measurements of human hepatic iron content will be made by the in vivo determination of magnetic susceptibility using a specially designed Superconducting QUantum Interference Device (SQUID) magnetic susceptometer. Our previous research has shown that these safe, rapid and sensitive magnetic measurements yield values for hepatic storage iron content which do not differ significantly from those obtained with chemical analysis of tissue obtained by percutaneous biopsy. Clinically, magnetic measurements of human iron stores will be used for the detection and serial monitoring of patients with iron overload syndromes (hereditary hemochromatosis, Thalassemia, refractory anemias, porphyria cutanea tarda, iron overload in chronic liver disease, inflammatory disorders and malignancy) to provide new information on the levels of body iron stores in these conditions and their change as a result of therapy or natural progression. Complementary theoretical and instrumental studies will be undertaken with the goals of increasing sensitivity in the measurement of iron excess, conducting pediatric studies and of achieving a methodological accuracy sufficient to detect iron deficiency. Magnetic measurements of hepatic iron rely on a fundamental physical property of storage iron and are free of the confounding influsnces which have limited the clinical usefulness of other measures of human iron stores.